When exposed to oxygen in the air, copper surfaces undergo a chemical reaction called oxidation. This reaction causes a fine crust or thin film to develop that constitutes a thin green protective layer of basic copper compounds (e.g., copper carbonate) referred to as patina. Patina can act to protect the original metal underneath it from further corrosion.
It can sometimes take several decades for this natural patination process to occur, depending on the environmental influences. For example, it took nearly thirty years for the Statue of Liberty to change from its original copper color to the iconic green that it is today.
Thus, while the end result is desirable and frequently found to be aesthetically pleasing, newly-installed architectural elements made from copper must undergo a series of color variations during the patination process and be subjected to conditions causing oxidation for a relatively long timeframe in order to achieve the desired visual effect of natural patina. Furthermore, repairing copper architectural elements that bear a patina can be difficult to perform in a way that allows the new replacement piece to be an appropriate color match so as to blend in with the surrounding portion of the copper architectural element being repaired.
Various reactive patina solutions or patina imitation treatments have been proposed which seek to imitate a natural patina but are capable of being produced in an accelerated timeframe. However, the prior approaches do not always produce a patina that favorably compares with a naturally-produced patina when considering its layer quality or coloration. Also, some prior reaction solutions are toxic, relatively costly to produce, and/or difficult to store. Furthermore, some patination processes can be complicated and difficult to perform.
As such, there is a continued need in the art to provide a patina solution for producing a patina on copper surfaces that is non-toxic and relatively simple to use in patination processes. Furthermore, there is a continued need for a process for producing a patina on copper surfaces in a short period of time (e.g., within a week) that more closely replicates the appearance of a naturally-produced patina occurring over years.
It will be appreciated that this background description has been created by the inventors to aid the reader, and is not to be taken as an indication that any of the indicated problems were themselves appreciated in the art. While the described principles can, in some respects and embodiments, alleviate the problems inherent in other systems, it will be appreciated that the scope of the protected innovation is defined by the attached claims, and not by the ability of any disclosed feature to solve any specific problem noted herein.